1. Field of the Invention
The present invention relates to a mobile robot such as a robot cleaner and, more particularly, to an apparatus and method for controlling an operation of the robot cleaner.
2. Description of the Conventional Art
In general, a mobile robot vacuum cleaner (hereinafter, ‘robot cleaner’) is a device for automatically cleaning an area by sucking debris such as dust from the floor while autonomously moving about in a room (e.g. a living room) of a house without a user's manipulation.
When cleaning, the robot cleaner recognizes a distance from itself to an obstacle such as furniture, office supplies or a wall in a cleaning area through a distance sensor and selectively controls a motor for rotating its left wheel and a motor for rotating its right wheel according to the recognized distance to change its direction and automatically clean the cleaning area. Herein, the robot cleaner performs the cleaning operation while moving around in the cleaning area through map information stored in an internal storage unit.
For example, the robot cleaner includes a gyro sensor for sensing a direction of the robot cleaner, an encoder for measuring a distance moved by sensing the number of rotations of a wheel of the robot cleaner, an ultrasonic sensor for sensing a distance between the robot cleaner and a target, and an infrared ray sensor for sensing an obstacle, and other numerous sensors.
However, the conventional robot cleaner has shortcomings in that because numerous high-priced sensors are installed to enable the robot cleaner to perform cleaning by precisely moving along a pre-set cleaning path, its internal structure is complicated and its fabrication cost increases.
In an effort to solve such a problem, a robot cleaner has been developed to perform cleaning by moving along an arbitrary cleaning path in a random manner.
A typical apparatus for operating a robot cleaner in accordance with the conventional art will now be described.
FIG. 1 is a block diagram showing the construction of an apparatus for operating a robot cleaner in accordance with a conventional art.
As shown in FIG. 1, the conventional apparatus for operating a robot cleaner includes: an obstacle sensing unit 1 for sensing an obstacle based on an impact amount generated when a robot cleaner going straight ahead in a specific area collides with the obstacle and generating an obstacle sense signal, a controller 2 for stopping movement of the robot cleaner based on the obstacle sense signal generated by the obstacle sensing unit 1, randomly generating a random angle, and generating a drive signal for rotating the robot cleaner according to the random angle, a left motor driving unit 3 for rotating a left motor (ML) 5 of the robot cleaner at a certain speed according to the drivel signal of the controller 2; and a right motor driving unit 4 for rotating a right motor (MR) 6 of the robot cleaner at a certain speed according to the drive signal of the controller 2.
FIG. 2 is a flow chart of a method for operating the robot cleaner in accordance with the conventional art.
First, when a user inputs a cleaning command signal (step S1), the controller 2 generates a drive signal to make the rotation speed of the left motor 5 and the right motor 6 equal in order to cause the robot cleaner to move straight ahead, and simultaneously outputs the drive signal to the left motor driving unit 3 and the right motor driving unit 4 (step S2).
The left motor driving unit 3 rotates the left motor 5 according to the drive signal of the controller. At this time, the right motor driving unit 4 also rotates the right motor 6 according to the drive signal of the controller 2. Namely, as the left and right motors 5 and 6 are simultaneously rotated, the robot cleaner moves straight ahead.
The obstacle sensing unit 1 senses an obstacle based on an amount of impact generated when the robot cleaner collides with the obstacle, generates an obstacle sense signal, and applies the obstacle sense signal to the controller 2 (step S3). If no obstacle sense signal is generated, the robot cleaner continuously performs cleaning operation.
The controller 2 stops moving of the robot cleaner according to the obstacle sense signal, randomly generates a random angle (step S4), generates a drive signal for rotating the robot cleaner according to the random angle, and then outputs the generated drive signal to the left and right motor driving units 3 and 4.
The left motor driving unit 3 rotates the left motor 5 according to the drive signal of the controller 2, and the right motor driving unit 4 also rotates the right motor 6 according to the drive signal of the controller. In other words, by relatively controlling the rotation speed of the left motor 5 and the rotation speed of the right motor 6 differently, the direction of the robot cleaner can be changed by the random angle (step S5).
Thereafter, when the robot cleaner is rotated by as much as the random angle, the controller allows the robot cleaner to again go straight ahead (step S6). When the cleaning operation of the robot cleaner is completed, the controller terminates the cleaning operation (step S7). If the cleaning operation of the robot cleaner is not completed, the controller allows the robot cleaner to repeatedly perform the cleaning operation routine.
In order to perform the cleaning operation, the related art robot cleaner includes a driving unit (not shown) having a suction motor and a wheel motor; a sensing unit (not shown) having a bumper sensor, a phase correction sensor and a cliff sensor; and a display module (not shown).
However, the related art cleaner has a problem that even when the cleaning operation is not performed, power of a battery is still supplied to the driving unit, the sensing unit and the display module, increasing power consumption of the battery. Namely, although the cleaning operation is terminated, power of the battery is continuously supplied to the units for performing the cleaning operation of the robot cleaner, unnecessarily consuming power of the battery.
U.S. Pat. Nos. 5,440,216 and 5,646,494 also disclose a robot cleaner.